The regular U.S. Army has an arsenal of various weapons, from small arms to anti-tank weapons. During Basic Training (BCT) every Soldier must qualify with his/her standard rifle, the M16 (America's Army models the M16A2, but the Army has transitioned to the M16A3 and M16A4 models). Soldiers also train with a variety of other weapons during BCT, including the M249 Squad Assault Rifle (SAW), the M67 Fragmentary Grenade and the AT4 Anti-Armor Rocket. Depending on a Soldier's particular Military Occupational Specialty (MOS) they might also train and qualify with weapons such as the M203 Grenade, the M2 .50 cal Machine Gun and/or the Javelin Missile System. Many Infantry and Ranger units now employ the M4A1 Carbine Rifle, a more compact variant of the M16, due to its success in close-quarters and urban combat environments. Today the M4A1 is often seen outfitted with a variety of special sighting attachments such as the M68 Aimpoint or the ACOG Reflex.